This invention relates to sidewall coring tools used to obtain samples of the formation through which a wellbore is drilled. In determining the physical properties of subterranean formations, it is of great assistance to have samples of the formation which are commonly called cores. A core is typically a cylindrical piece of the rock which has been cut from the underground formation and can vary in size and length. A typical size is 1/2 inch in diameter and 4 to 6 inches long although samples can be of larger diameter and of greater length, depending on the facilities available. One type of core cutter is the type that can be used to cut the cores from the sidewall of a borehole after the borehole has already been drilled. Such a sidewall coring tool is described in U.S. Pat. No. 4,280,569, issued July 28, 1981 to Houston B. Mount, II, inventor, and Standard Oil Company (Indiana) assignee. This invention relates to such a sidewall coring tool.